MADISON -- Three years ago Todd Bol came up with an idea to remember his mother, a teacher who had loved books and encouraged people to read. At his home in Hudson, Wisc., he built a box, made it waterproof and filled it with books. It looked like a miniature one-room schoolhouse, with a sign underneath that said “Free Book Exchange.” Bol put it on a post outside of his house and invited neighbors to take a book, and return a book.

That’s when something happened Bol says he never could have imagined.

“People of all ages, men, women, kids came up and just loved the library,” he said. “They got excited and they started coming up to me saying, ‘I’ll build one, do you need books?’”

The idea has mushroomed. Bol now encourages people to visit his website for suggestions on how to build their own library.

Today there are Little Free Libraries in at least 28 states and six countries including Ghana, Australia and Afghanistan. And people from more than a dozen other countries have expressed interest, Bol said.

On Bol's website he offers suggestions on how to build the libraries and sells kits for a fee starting around $100. Money donated to his non-profit helps build libraries in needy communities and developing countries. The website says, "If you need help let us know. Don't let money get in the way."

You can find the little libraries not just in front of homes, but also outside of health centers, coffee shops, bike paths, bus stops and store fronts. People are encouraged to send in a picture of their library so it can be posted on the website. In return they get a "Little Free Library. Take a Book, Return a Book" sign to post on what they've built, as well as a Little Free Library Charter number.

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NBC's Rehema Ellis speaks with Little Free Library creator Todd Bol in front of one of his little free libraries, covered and designed
with birch bark.

Each library is unique.

"I've worked with people who will take pieces of their home or their old farm and they'll incorporate it into a library," Bol said.

Some are made from old cranberry crates, or metal milk cartons, with hinges from old refrigerators. In New Orleans, La., Bol said some libraries have been built using debris from Hurricane Katrina. People will decorate them based on themes from their favorite books, such as “Jack and the Bean Stalk.”

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A local artist from Madison, Wisc., was commissioned to create a canine-themed Little Free Library designed to be installed near a dog park.

And each one has become more than just a place for getting books and leaving books. Bol said the little libraries have fostered a greater sense of community.

“There’s a primal need,” he said, “for people to be a part of their community. We have people tell us all the time in seven days of having a Little Free Library I’ve met more people than I have met in 20 years in my neighborhood.”

In Madison, Wisc., Meghan Blake-Horst put a little library in her front yard. "It's a continual conversation piece," she said.

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Amy Poland walks by this little free library on the corner of her street in Madison, Wisc., every day.

Terri Connolly Cronk, who also lives in Madison, said people in the neighborhood who never stopped and talked before are stopping now because of the library that rests on the corner of her property. The library is not just encouraging readers, it's giving neighbors opportunities to get to know each other.

Part of the allure of the Little Free Libraries, Bol said, is that you don’t need a library card. There are no fees, no fines and no operating hours. The Little Free Libraries are open for business 24/7. So any time of day, people can get a book or share a book, hopefully a page turner.

Now one can only imagine that in this age of electronic books, Todd Bol’s mother would have loved how his story to honor her is turning out.